For overhead street lighting, it is desirable that the street be generally symmetrically illuminated, so that one side of the street is not significantly brighter than the other side. It is also desirable that the light that produces such illumination may be located relatively close to one side of the street, so that the pole that suspends it above the street need not extend halfway across the street. While overhead street lighting is used as an example, it should be recognized that there are many other applications where asymmetrically distributed illumination is desireable.
As a result, there exists a need for an optical system that can produce asymmetrically distributed illumination.
Furthermore, as light emitting diodes (LEDs) become more commonplace and less expensive in general illumination applications, it may be desirable to incorporate LEDs as the light sources in overhead street lighting and other systems.
Accordingly, there exists a need for an optical system using an LED light source that can produce asymmetrically distributed illumination.